Hydraulic jack



Jan. 2l,

Filed June 10. 1927 T. c. PoMr-:ROY

HYDRAULIC JACK HTTon/veys T. c. PoMERoY HYDRALIG 'JACK A Jan. 21, 1930.

2 Sheets-Sheet 2 Filed June 10' 1927 E YPH INVE/vToR 77M07'Hy6. POM/m05 By @Wfl mmf' /7 T TRNELVS Patented Jan. 2 1, 1930 'rnito'rnv c. ronEEoY, 'or noon ISLAND, ILLINoIs Application llcl June 10, 1927. Serial No. 197,853.

This invention relates to new and useful l improvements in hydraulic jacks and more particularly to such jacks of the t pe shown 1n mv pending application, erial No. s 110,177,1i1ed May 19, 192e. l An object of this invention is to provide a hydraulic jack comprising a cylinder having a hollow plunger operable therein, and theplunger having a lifting head terminally mounted thereon, and a plug valve being mounted in the lifting head to which a pump is connected, and, to which also is connected an expansion chamber having a`duct connectv ing it with the plunger whereby, when the Huid in the jack expands from increasing temperatures, a portion of the fluid will flow into the expansion chamber, thus preventing excessive internal strains from being built up within the jack.

A further object of the inventionis to provide in connection with sucha jack, an expansion chamber having a connection with the interior of the plunger so that a portion of the fluid may flow thereinto when the fluid expands, and whereby the expansion chamber may also function as an auxiliary reservoir adapted to receive a portion of the oil when the latter expands, thereby preventing the loss of oil as a result of expansion, and the oil received in the expansion chamber being retained therein until the jack is operated, when it will be drawn back into the plunger, thus providing means for maintaining a given quantity of fluid in the jack at -all times.

The particular object of the invention therefore is to provide an improved hydraulic jack that cannot leak.

Other objects vof the invention will appear from the following description and accornpanying drawings and will be pointed out in the annexed claims.

In the accompanying drawings there has been disclosed a structure designed to carry out the various objects of the invention, but

it is to be understood that the invention is not confined to the exact features shown as various changes may be made within the 0 scope of the claims which follow.

In the accompanying drawings forming part of this specification:

Figure lis a vertical sectional view of a hydraulic jack showing in dotted lines the invention applied thereto;

Figure 2 is a detailed sectional view showing the check valve opening members in normal inoperative position;

Figure 3 is a sectional plan view-on the line 3-3 of Figure 1;

Figurev 4 is a vertical sectionaldetailed view on the line 4-4 of Figure 3;

Figure 5 is a detailed sectional view on the line 5--5 of Figure 3, showing'the air vent in closed position as when the jack is folded; and

Figure 6 is .a similar view showing the vent in open position as when the pump is extended to an operative position.

In the selected embodiment of the invention here shown, for purposesof disclosure, there is illustrated a jack of the type shown in the above mentioned pending application, comprising a cylinder 11 having its lower end seated in a suitable base 12 and further having a disc-like plate 13 mounted in the lower end thereof for strengthening the walls of the cylinder.

A hollow plunger 14 is mounted within the cylinder 11 and has a cap 15 secured to the lower end thereof against which a packing 16 is seated as shown in Figure 1. A circular plate 17 is clampingly engaged with the packing 16 by means of nuts 18 and 19 received in threaded engagement respectively with a discharge pipe 21 and an intake pipe or tube 22 having their lower endsreceived in aligned apertures provided in the cap 15, packing 16, and plate 17. A port 23 is 'provided in the intake pipe 22 to establish communication between the pipe and the interior of the plunger 14. It will also be noted by reference to Figure 1, that the cap 19 provides a closure for the lower end of the tube 22, but that the cap 18 is open, whereby the tube 21 communicates with the lower end of the cyljinder beneath the packing 16. The upperend of the cylinder is internally tapered to receive a packing gland 24 having a conical face 25 cooperating with a similarly shaped face 26 in a packing nut 27 to force a acking 28 against the walls of the plunger.

hen the nut 27 is tightened, the gland 24, nut 27, and .packing 28 co-operates to provide a leak-proof joint between the upper end of the cylinder and the wall of the plunger 14. The outside diameter of the plunger 14 is preferably less than the inside diameter of the cylinder 11 so as to provide an annular chamber 29, communicating with the interior of the plunger 14 through a duct 31, provided in the wall of the plunger adjacent the lower end thereof.

A lifting head 32 is terminally seated upon the upper end of the plunger 14 and has threaded sockets in the lower portion thereof, adapted to receive the upper threaded ends of the tubes 21 and 22. By thus securing the tubes to the lifting head 32, the plunger assembly including the lifting head 32, plunger 14, cap 15, packing 16, plate 17, and the tubes 21 and 22, may be securely clamped together as a unit by tightening the nuts 18 and 19 engaged with the lower ends of the tubes 21 and 22.

A plug valve 33 .is mounted in a tapered bore 34 provided in the lifting head 32, and this plu valve has a pump operatively connected t erewith which comprises an inner section 35 pivotally connected with an outer section 36 by means of a tapered joint 37, shown in Figure 1. A displacement rod 38 is reciprocally mounted in the section 36 and has an operating handle 39 secured to the outer end thereof for the convenience of the operator in actuating the rod 38 to pump the fluid from the plunger into the cylinder beneath the packing 16. The pump section 35 is secured to the plug valve 33 by means of a hub 41, rovided at one end thereof as shown in Figure 3. A duct 42 connects the pump with a groove 43 provided in the periphery of the valve 33. (See Flgures 1, 2, and 3.) The plug valve 33 is retained in the tapered bore 34 by means of a cap 44 mounted upon a reduced extension 45 of the valve and retained thereon by means of a pin 46, shown in Figure 3.' A disc or washer 47 isv seated against one end of the hub 48 in which the plug valve is mounted and has a compression spring 49 yieldably holding it against the end of the hub as shown in Figure 3. The other end of the spring 49 is seated against theV cap 44. It will also be noted by ref- .erence to Figure 3 that the aperture 51 1n the disc 47 is relatively larger in diameter than the extension 45 of the plug valve, so that an air circulating passage is provided therebetween. The outer end of the extension 45 is similarly fitted in the cap 44.

Fluid passages 52 and 53 are provided in the lifting head 33 and communicate respectively with the discharge tube 21 and intake tube 22 as shown in Figure 1. A spring actuated check valve 54 is provided in the fluid assage 52 and a similar valve 55 is provided 1n the passage 53. The fluid passage 52 communicates with the plug valve 33 through a chamber 56, having a Valve-unseating member 57 mounted therein, one end of which is adapted to engage a cam or raised portion 58 provided on the plug valve 33. This valveopening member also has a head 59 having fluid channels 6l therein, through which the oil will flow from the plunger to the pump and from the pump to the cylinder during the, operation of raising the jack. A compression spring 62 constantly urges the head 59 of the member 57 against the cam 58 or against the bottom ofthe groove 43 in the plug valve, as shown in Figure 2. A relatively smaller valve opening member 63 is mounted in a chamber 64 and has one end adapted to engage the valve 55 to move it into open position, shown in Figure 1. The other end of this valve-opening member is similarly engaged with the cam 58 by means of a compression spring 65. In Figure 1, the plug valve 33 is shown rotated to a position Wherein both valve-opening members have been actuated to open their respective valves. When the valves are thus positioned, the oil or fluid will flow from the bottom of the cyl,- inder, through the pipe 21, passage 52, Valve 54, chamber 53, and through the open valve 55, tube 22, thence through the duct 23 and into the plunger 14. Figure 2 illustrates the position of the valve-opening members 57 and 63, when the plug valve 33 is positioned to permit the pump' to be operated to raise the plunger. When .the plug valve is positioned as shown in Figure 2, the two check valves will be in closed operative position.

In jacks of this type, it is desirable that means be provided, for taking care of the expansion of the fluid caused by extreme changes in temperature.

A feature of this invention resides in the provision of an expansion chamber in connection with the jack which has communication with the interior of the plunger and is so arranged that lwhen the fluid in the jack expands, it will low into the expansion chamber, and, when the fluid cools, it will be returned to the interior of the jack. This eX- pansion tank is shown in dotted lines in Figure 1 and full lines in Figure 4, and comprises a tubular member 66 having its upper end received in threaded engagement with a socket 67 provided in a depending hub 68 preferably integrally formed with the lifting head 32. A cap 69 is received in threaded engagement with the lower end of the member 66 to provide a closure therefor. A tube 71 is mounted within the tubular member 66 and has its upper end received in threaded vengagement with the lifting head 32. This tube communicates with the annular groove,` 72 provided in the plug valve 33, as shown in Figures 3 and 4. The lower open end of the tube 71 is spaced from the cap 69, and a duct 73 connects the annular groove 72 in the plug valve with the interior of the plunger 14 as shown in Figure 4. A filler cap 74 is provided in the lifting head 32 through which oil may be introduced into the plunger 14 and into the annular space 29 provided between the wall of the plunger and the Wall of the cylinder 11.

A breather or vent is also provided for permitting air to be drawn into the plunger during the operation of transferring the fluid from the plunger into the cylinder to raise the lifting head. Such means is shown in Figures 5 and 6 and comprises a small duct 75 communicating at one end with the interior of the tubular member 66 and having its other end adapted to communicate with a notch 76 provided in the periphery of the plug valve 33adjacent the cylindrical extension 45 thereof. When the plug valve is positioned as shown in Figure 6, or when the pump is in its operative position, the interior of the tubular member 66 will, when empty,

i; be in communication with the atmosphere through the duct 75, notch 76, aperture 51, and through the aperture provided in the cap 44 in which the extension is received. lrVhen the plug valve 33 is positioned as shown in Figure. 5, or as when the pump section 35 is positioned as shown in Figure 1, the vent duct 75 will be closed to prevent leakage of fluid therethrough, when the jack is stored away in a toolbox.

In the operation of this novel jack and assuming that the temperature is normal, the plunger and cylinder are filled with fluid as shown in Figure 4, or until the fluid overflows from the filler opening in the lifting head. lVhen thus initially filled, no fluid is received in the tubular member 66. Thus, it will readily be seen, by reference to Figure 4, that when the fluid within the cylinder and plunger expands from rising temperatures,

' the fluid will flow from the upper end of the plunger through the duct 73, annular groove 7 2, tube 71 and into the member 66, thus positively preventing internal strains from being built up within the jack as a result of such expansion of the fluid. Also, by providing such an expansion chamber4 in connection with the jack, the danger of leakage is minimized as there is no tendency of the oil being forced through the packings of the jack as would result in the event that no means were provided for taking care of the expansion of the fluid. The expansion chamber also functions as an auxiliary reservoir for` storing additional fluid, whereby the plunger may be raised to its maximum height within the cylinder.

I claim as my invention:

1. In a hydraulic jack, the combination of a cylinder having a plunger movable therein, a. lifting head secured to the plunger, a. plug valved in the head having aipump operatively connected therewith, valve passages in the head connecting the plug valve with the eylinder and plunger, an expansion chamber secured to said head and depending therefrom, an air duct connecting said expansion chamber with said plug valve to provide a-brcather for the chamber, said plug valve being adapted to open and close said air duct, and a tube mounted within said expansion chamber and having one end communicating with said plunger whereby expanding fluid will be discharged from said plunger into said expansion chamber.

2. In a hydraulic jack, the combination of a cylinder having a plunger movable therein, a lifting head secured to the plunger, a plug valve in the head having a pump connected therewith for transferring the fluid from the interior of the plunger to the lower end of the piston beneath the plunger, valved passages in the lifting head connecting the plug valve with the cylinder and plunger, an expansion chamber secured to said lifting head beneath said plug valve, an air vent for the expansion chamber, and a tube positioned within the chamber associated with said plug valve and adapted to be opened and closed by rotation thereof, and having a connection with the plunger whereby expanding lluid in the plunger will be delivered to said expansion chamber, the lower end of the tube being positioned adjacent to the bottom of the expansion chamber and spaced therefrom.

3. In a hydraulic jack, the combination of a cylinder having a plunger movable therein, a lifting head secured to the plunger, a plug valve in the head having a pump connected therewith for transferring the fluid from the interior of the plunger to the lower end of the piston beneath the plunger, valved passages in the lifting head connecting the plug valve with the cylinder and plunger, an expansion chamber secured to said lifting head beneath said plug valve, an air vent for the expansion chamber, and a tube positioned within the chamber associated with said plug valve and adapted to be opened and closed by rotation thereof, and constantly communicating with the plunger through said plug valve, whereby expanding fluid in the plunger will be delivered to said expansion chamber, the lower end of the tube being spaced from the bottom of the expansion chamber.

4. In a hydraulic jack, the combination of a cylinder having a plunger movable therein, a lifting head secured to the plunger, a plug valve in the head, a pump operatively connected therewith, said head having valved passages therein connecting said plug valve with the cylinder and plunger, said head also having an expansion chamber depending therefrom exteriorly of the cylinder and said chamber having an air vent communicating with said plug valve, and means on said plug valve adapted to open said vent to the atmosphere when the p unger is: operated to raise the plunger, and adapted to close said vent when the ump is in an inoperative position. 5. In a ydraulic jack, the combination of a cylinder having a plunger movable therein, a lifting head secured to the plunger and having a. tapered bore therein, a plug valve in said bore, a pump operatively connected 1p with said plug valve, said head having valved passages therein connecting said bore with the cylinder and plunger, sald head also having an expansion chamber communicating with said tapered bpre and the expansion chamber having a vent connecting the upper end thereof with one end of said tapered bore, and means adjacent one end of said plug valve adapted to open said vent to the atmosphere, when the pump isl operated to raise the plunger, and adapted to close said vent when the pump is in an inoperative position.

6. In a h draulic jack, the combination of a cylinder aving a hollow plunger therein, a. lifting head secured to the plunger and having a tapered bore therein, a plug valve in said bore having a duct therein, a foldable pump connected with one end of said plug valve and communicating with said duct, said head having valved passages therein connecting said duct with the cylinder and plun er, said head also having an expansion cham er communicating with said tapered bore and the interior of saidplunger, said expansion chamber having a vent connecting it with said tapered bore, and means in the periphery of said plug valve adapted to close said vent to the atmosphere, when the pump is in a folded inoperative position, and adapted to open said vent to the atmosphere when the pump is in an operative position.

In witness whereof, I have hereunto set my hand this 6th day of June 1927.

TIMOTHY C. POMEROY. 

